AT&T UNIX™PC Unix System V Users Manual - tenox

TSEARCH ( 3C ) TSEARCH ( 3C )
data type typedef enum { preorder, postorder, endorder, leaf }
VISIT; (defined in the header file), depending on
whether this is the first, second, or third time that the node has
been visited (during a depth-first, left-to-right traversal of the
tree), or whether the node is a leaf. The third argument is the �
level of the node in the tree, with the root being level zero. ·�
The pointers to the key and the root of the tree should be of type
pointer-to-element, and cast to type pointer-to-character. Similarly,
although declared as type pointer-to-character, the value
returned should be cast into type pointer-to-element.
EXAMPLE
The following code reads in strings and stores structures containing
a pointer to each string and a count of its length. It then
walks the tree, printing out the stored strings and their lengths in
alphabetical order.
#include
#include
struct node { /*pointers to these are stored in the tree*/
char *string;
int length;
};
char string_space[lOOOO];
struct node nodes[500J ;
struct node *root = NULL;
root*/
main( )
{
}
I*
char *strptr = string_space;
struct node *nodeptr = nodes;
void print_node( ), twalk( );
int i = 0; node_compare( );
/*space to store strings*/
/*nodes to store*/
/*this points to the
while (gets(strptr) != NULL && i++ < 500) {
/*set node*/
nodeptr- >string = strptr;
nodeptr- > length = strlen(strptr);
j*put node into the tree*/
(void) tsearch(( char *)nodeptr, (char **)
&root,
node_compare );
/*adjust pointers so we don't overwrite
tree*/ �
strptr += nodeptr->length + 1;
l
nodeptr++;
}
twalk((char *)root, print_node);
This routine compares two nodes, based on an
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